In connection with the sewing of designs and other patterns on work pieces such as garments or cloth, it is often desired to use threads of various types and colors in the sewing or embroidery of a given design. When a sewing or embroidery machine is used, the thread used may be changed by manually removing a thread and rethreading the machine with another thread. Another method of providing for numerous threads is to employ a machine which uses a number of needles and associated mechanisms, each of which is threaded with a different thread. In such a system, availability of a large number of threads requires a complex machine having separate needle assemblies for each type of thread in use. As the desired number of threads increases, the complexity and cost of the machine necessarily increases.
In machines having a single needle, threads may be changed by splicing the first thread to a second thread in a manner which enables the splice to be drawn through the eye of the needle, effectively threading the needle with the second thread. It is known that a splice may be formed by placing the two threads to be spliced in close proximity to each other and subjecting the threads to a jet of air at relatively high velocity. The jet of air causes a portion of the fibers of the threads to interlace along a region of both threads. The interlacing of the fibers is intended to form a splice of sufficient strength and desired size such that the spliced portion can readily pass through the eye of the needle.
Although it is known to use an air jet to splice two threads, it would be advantageous to provide a sewing machine with an integrated thread changing capability for effectively and efficiently handling all weights and types of threads. Such a capability should be provided in a cost effective manner of both construction and operation. It would also be desirable to provide such a machine with the capability of selecting from a large number of thread types and colors by providing an efficient mechanism for the supply of such threads. Such a machine having thread changing capability would also desirably include the feature of being able to adjust the tension of the threads for most effective sewing. It would also be advantageous to expeditiously and efficiently select new threads and to execute a thread change which wastes the minimum amount of thread. A further advantage would be to have the thread selection, thread changing, and tension adjustment be accomplished under programmable control.